1. Field of the Invention
The present invention is generally concerned with clutch release bearings, and more particularly with clutch release bearings for automotive vehicles.
2. Description of the Prior Art
As is known, a clutch release bearing is designed to act on the clutch release device of a clutch mechanism. It generally comprises an actuator member whereby is is adapted to act on the clutch release device and an operating member whereby it is adapted to be acted on, either directly or indirectly, by a control member, in practice usually referred to as a "yoke", the actuator member being axially coupled to the operating member by a cover.
The present invention is more particularly concerned with clutch release devices which are designed to apply traction to the clutch release device of the clutch mechanism concerned.
A plate, usually referred to as a bearing plate, is then associated with the operating member of the clutch release bearing, to be acted on by the control yoke or clutch release yoke. This plate may be subdivided to form two diametrically opposed arms on which said control yoke may bear in the axial direction, from the side facing the actuator member.
As the cover is usually a metal part while the operating member is usually of a synthetic material, it would be beneficial to have the bearing plate form part of the cover, rather than part of the operating member as is usual, the corresponding part of the operating member, generally a flange, then having to be itself faced with a metal plate forming a bearing plate to minimize the inevitable wear due to the axial force applied by the control yoke when in service.
There then arises the problem of fastening the cover to the operating member so as to axially couple the actuator member to the latter.
This fastening is usually implemented by crimping the axially oriented annular side wall which the cover usually comprises to the perimeter of the transversely disposed flange which the operating member usually comprises.
As a general rule, in the case of a clutch release bearing designed to push on the clutch release device of a clutch mechanism this crimping is relatively easy to implement as it concerns only the clutch release bearing, taken in isolation. This does not apply when, as in this instance, the clutch release bearing is designed to pull on the clutch release device.
In the latter case, the crimping can be effected only when the clutch release bearing is already at least partially coupled to the clutch release device in question, by its actuator member, being therefore somewhat difficult and delicate to carry out under these conditions.
This difficulty is inevitably increased if the associated bearing plate forms part of the cover.
In this case the bearing plate is adjacent that part of the annular side wall of the cover to be crimped, impeding execution of the operations required to effect the crimping.
Furthermore, there are two requirements to be met simultaneously. One concerns the fact that, in order to be able to resist the axial force applied by the control yoke, the metal constituting the bearing plate must be treated so as to improve its resistance to wear, which reduces its ductility. The other is concerned with the fact that, in order to bend readily on crimping, the metal constituting the cover must offer good ductility.
It will be obvious that these two requirements can be reconciled only with difficulty when the bearing plate forms part of the cover, the metal necessarily being the same in both cases and thus not being treatable in its entirety.
A general objective of the present invention is an arrangement enabling these disadvantages to be overcome and conferring other advantages.